An agricultural harvester known as a “combine” is historically termed such because it combines multiple harvesting functions with a single harvesting unit, such as picking, threshing, separating and cleaning. A combine includes a header which removes the crop from a field, and a feeder housing which transports the crop matter into a threshing rotor. The threshing rotor rotates within a perforated housing, which may be in the form of adjustable concaves and performs a threshing operation on the crop to remove the grain. Once the grain is threshed it falls through perforations in the concaves onto a grain pan. From the grain pan the grain is cleaned using a cleaning system, and is then transported to a grain tank onboard the combine. A cleaning fan blows air through the sieves to discharge chaff and other debris toward the rear of the combine. Non-grain crop material such as straw from the threshing section proceeds through a residue handling system, which may utilize a straw chopper to process the non-grain material and direct it out the rear of the combine. When the grain tank becomes full, the combine is positioned adjacent a vehicle into which the grain is to be unloaded, such as a semi-trailer, gravity box, straight truck, or the like; and an unloading system on the combine is actuated to transfer the grain into the vehicle.
More particularly, a rotary threshing or separating system includes one or more rotors which can extend axially (front to rear) or transversely within the body of the combine, and which are partially or fully surrounded by a perforated concave. The crop material is threshed and separated by the rotation of the rotor within the concave. Coarser non-grain crop material such as stalks and leaves passes through a straw beater to remove any remaining grains, and is then transported to the rear of the combine and discharged back to the field. The separated grain, together with some finer non-grain crop material such as chaff, dust, straw, and other crop residue are discharged through the concaves and fall onto a grain pan where they are transported to a cleaning system. Alternatively, the grain and finer non-grain crop material may also fall directly onto the cleaning system itself.
A cleaning system further separates the grain from non-grain crop material, and typically includes a fan directing an airflow stream upwardly and rearwardly through vertically arranged sieves which oscillate in a fore and aft manner. The airflow stream lifts and carries the lighter non-grain crop material towards the rear end of the combine for discharge to the field. Clean grain, being heavier, and larger pieces of non-grain crop material, which are not carried away by the airflow stream, fall onto a surface of an upper sieve (also known as a chaffer sieve) where some or all of the clean grain passes through to a lower sieve (also known as a cleaning sieve). Grain and non-grain crop material remaining on the upper and lower sieves are physically separated by the reciprocating action of the sieves as the material moves rearwardly. Any grain and/or non-grain crop material remaining on the top surface of the upper sieve are discharged at the rear of the combine. Grain falling through the lower sieve lands on a bottom pan of the cleaning system, where it is conveyed forwardly toward a clean grain auger. The clean grain auger conveys the grain to a grain tank for temporary storage. The grain accumulates to the point where the grain tank is full and is discharged to an adjacent vehicle such as a semi trailer, gravity box, straight truck or the like by an unloading system on the combine that is actuated to transfer grain into the vehicle.
The separating system directs the non-grain material and chaff, along with the courser non-grain material such as stalks and leaves coming from the straw beater, toward a residue handling system that processes and/or spreads the residue upon the field. The prior art mostly relies upon airflow generated by the primary cleaning fan to move non-grain material, residue, and chaff through the residue handling system. As a result, not uncommonly certain areas of the residue handling system may suffer from the formation of vortices within the flow of airborne material other than grain (MOG) under certain operating conditions, particularly when the combine is experiencing low throughput. This is especially true when at least part of the flow of airborne MOG passes between the straw beater and a subsequent residue treatment device such as a chopper. The formation of vortices in the flow of airborne MOG tends to result in clogging, especially when the vortices form in areas of airborne MOG containing the courser non-grain material.
Some embodiments of the prior art have provided additional fans, including adjacent to the straw beater. However, none address the problem of formation of vortices between the straw beater and a subsequent residue treatment device within the residue handling system. Canadian Patent No. 991,938 discloses the use of auxiliary blowers, but they adjoin the primary cleaning fan, not the straw beater. Canadian Patent No. 1,280,660 discloses the use of a pair of fans located adjacent to the straw beater, but they are used to draw a strong current of air along the outer surface of the threshing cage, in order to minimize the effects of turbulent air being expelled from the threshing cage. The '660 patent states that, “It is noted that the end of the discharge beater, which is located at the end of the threshing cage, does not do any significant propelling of the rotor discharge out the rear thereof, and thus locating fans adjacent the end of the beater does not significantly impact on the discharge of the material other than grain out the rear of the threshing cage.” The '660 patent does not disclose using the pair of fans located adjacent to the straw beater to prevent formation of vortices between the straw beater and any subsequent residue treatment device, as no subsequent residue treatment device is shown.
U.S. Pat. No. 713,229 similarly discloses a pair of fans located adjacent to the straw beater, but, again, does not disclose using the pair of fans to prevent formation of vortices between the straw beater and a subsequent residue treatment device. U.S. Pat. No. 925,002 similarly discloses a pair of fans located adjacent to a straw beater, but the pair of fans are used to scatter grain and MOG onto the sieves. European Patent No. 1,187,526 discloses the use of a pair of fans located adjacent to the residue chopper, rather than adjacent to the straw beater. They are used to discharge MOG from the straw and chaff spreader, not to prevent the formation of vortices between the straw beater and the residue chopper. U.S. Pat. No. 6,113,491 and U.S. Published Application No. 20040043804 similarly disclose fans located adjacent to the residue chopper, which are used to help discharge MOG from the chopper and/or spreader.
Published PCT Application No. 2005022980 discloses essentially two embodiments. One involves a chopper located at the end of the rotor and concaves, in lieu of a straw beater, which chopper has fans adjacent to it. These fans direct the flow of MOG through a plenum and over a tailboard for distribution on the field. Alternately, the airflow from the fans is directed in parallel with the plenum through separate ducts before joining the flow of MOG at the tailboard. No subsequent residue treatment device is shown. Therefore, this embodiment does not address the problem of the formation of vortices between the straw beater and any subsequent residue treatment device. Another embodiment involves a “conventional rear mounted straw chopper.” In this embodiment, the additional fans are either adjacent to the chopper, or located elsewhere and the flow therefrom ducted to the chopper. This embodiment also does not address the problem of the formation of vortices between the straw beater and any subsequent residue treatment device, because the flow is not directed between the straw beater and subsequent residue treatment device.
What is needed in the art is a residue handling system that avoids the formation of vortices in the flow of airborne MOG between the straw beater and a subsequent residue treatment device under all operating conditions, especially within the flow of airborne MOG containing courser non-grain material.